PMON106 Persistent Prolactin Levels in a Patient with Pituitary Adenoma

We present a peculiar case of persistently elevated prolactin levels with significant residual tumor in the setting of dopamine agonist therapy.This is a 45 year old male with no known medical history who presented with a seizure. Work up was significant for a large homogeneously extra-axial mass (57×35×44 mm) arising from the left clinoid extending anteriorly, inferiorly, and posteriorly to the planum sphenoidale, the sphenoid sinus, and the suprasellar cistern, respectively. The mass extended superiorly to compress the hypothalamus, and medially to the right cavernous sinus. This mass was causing elevation of the optic chiasm and encasement of the left optic nerve and the left internal carotid artery with displacement of the pituitary infundibulum to the right. Biochemical workup revealed hyperprolactinemia with a prolactin level greater than 2000, and secondary hypogonadism; free testosterone level of 27.1. He was started on therapy with a dopamine agonist, cabergoline at 0.5 mg. This dose was up titrated to a max dose of 12 mg weekly over 6 months. Subsequently, prolactin levels trended down from initial levels of >2000 to 1142 to 1115 to 1045 to 710 with corresponding increases in cabergoline. He began to experience CSF rhinorrhea. Neurosurgery recommended medical therapy given the high risk anatomical location of the prolactinoma. In our interdisciplinary conference, discussion was had regarding other therapeutic agents. Patient was started on anastrozole and metformin. He subsequently started somatostatin, as well. Patient underwent a repeat MRI Sella on 9/2021 with a 50% decrease in size. Most recently, the patient has had a repeat seizure and is scheduled for a repeat MRI with possible consideration of surgical resection despite the high risk surgery.Current guidelines suggest symptomatic patients that do not achieve normal prolactin levels or show significant reduction in tumor size on standard doses of a dopamine agonist should be increased to maximal tolerable doses before referring for surgery There is literature regarding alternative treatment options in the setting of elevated prolactin levels with a discordant response to first line therapy. Options include switching to another dopamine agonist, radiotherapy, or alternative options. One of these options include aromatase inhibitors, with inhibitory effects on prolactin gene transcription. There are studies that outline use of Temzolamide for aggressive pituitary tumors and carcinomas, however, there is not enough data regarding its use in resistant Prolactinomas. Lastly, somatostatin analogues have been shown to reduce prolactin levels due to the presence of somatostatin receptors in prolactinomas. A published case series (Sosa-Eroza et al.) showed 5 patients with DA resistance with two cases with reduction in tumor volume and prolactin level. Our patient has had a response to sandostatin with most recent prolactin levels 111. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.